Deleteing from some tables....

Posted on 2000-02-24
Medium Priority
Last Modified: 2010-04-04
I have made a simple database containing two tables, one is the master of the other.

The first one is a table of files. The second is a table of discs that these files are stored on.

Files.db and Discs.db.

I have a query for showing this in a TDBGrid with the SQL below:

Select Files.FileName, Discs.Label from Files, Discs
  where Files.Disc = Discs.ID
order by Files.FileName, Discs.Label

This query has an UpdateSQL connected to it.

I also have a separate Query for the discs with the following SQL:

Select ID, Label from Discs

This query is just for showing a list of the discs in a separate TDBGrid.

Now I want to be able to select a disc from the disc-grid and have my program to delete that disc from the database including all of its detail files. For this I have yet another query, the EraserQuery. Here's the SQL for that one:

Delete from Files
  where Disc = :CurrentDisc

"CurrentDisc" is defined below, it is for the program to know which disc the user has selected. -

procedure TModules.DiscQueryBeforeDelete(DataSet: TDataSet);
  EraserQuery.ParamByName('CurrentDisc').AsInteger := Discs.FieldByName('ID').AsInteger;

This works fine with the deletion and all, but it doesn't update the first query, the one showing all files and which disc they're on. It updates the tables and I have to restart my program for it to get updated. What can I do to fix this? Is there a better way deleting detailrecords?


Question by:sageryd
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
  • 2
LVL 27

Expert Comment

ID: 2555031
does a close and reopen of the first query not solve the problem without starting the whole app?

Expert Comment

ID: 2555146
A Refresh should normally do fine.

(Question: Is the query updated when you move a record in the first table and then move back to the record)

Author Comment

ID: 2555345
It works when i close and re-open the first query, but then I lose the selection the use might have. Is there another way? Refresh doesn't work.

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.


Expert Comment

ID: 2555365
Hi sageryd,

perhaps bookmarking it, before closing? (don't know if this works)

Or, get the recordnumber  (thus position of record)

and then after closing do a  

query.First (not needed I think)
query.MoveBy(recordnumber) ?

LVL 27

Accepted Solution

kretzschmar earned 400 total points
ID: 2555533
hi zif,

recordnumber is not on all databases properly filled,
also it is not properly filled, if not all records are fetched.

if zif suggestion will not work,
then save a unique fieldvalue into a var and
after open the query do a locate with it


Author Comment

ID: 2555782
well, ok thanx! I guess Meikl should get the points as he was the first to give an answer.

Thanks again!



Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Introduction I have seen many questions in this Delphi topic area where queries in threads are needed or suggested. I know bumped into a similar need. This article will address some of the concepts when dealing with a multithreaded delphi database…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…
Have you created a query with information for a calendar? ... and then, abra-cadabra, the calendar is done?! I am going to show you how to make that happen. Visualize your data!  ... really see it To use the code to create a calendar from a q…
Suggested Courses
Course of the Month13 days, 17 hours left to enroll

800 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question